Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enzymes of DNA synthesis, thymidine kinase (ATP-thymidine-5'-phospho-transferase, EC 2.7.1.21), DNA polymerase (EC 2.7.7.7) and nuclease activities were investigated in isolated purified nuclei of swine aorta. Thymidine kinase which is detectable in these nuclei can be stimulated by the addition of phospholipase C. DNA polymerase activity of isolated nuclei is strongly dependent on addition of an exogenous template; the preferred template is activated DNA. The activity in the absence of an added template is very low except when labelled dCTP is used as the precursor. This incorporation of labelled dCTP does not require the addition of the other three triphosphates, and under these conditions, dCTP seems to be incorporated into what may be a homopolymer. As with other tissues, solubilized preparations of aortic nuclei have two DNA polymerase activities which also prefer activated DNA template. There is no detectable endonuclease in aortic nuclei.
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PMID:Enzymes of DNA synthesis in isolated nuclei of swin aorta. 94 21

In a previous paper, we determined that treatment of lymphocytes with nonviable preparations of human immunodeficiency virus type 1 (HIV-1) results in an impairment of the phosphatidylinositol/protein kinase C pathway, most likely due to an inhibition of the cleavage of phosphatidylinositol bisphosphate into inositol trisphosphate and diacylglycerol, mediated by phospholipase C. Here we show that one consequence of these changes is a reduced phosphorylation of nuclear matrix-associated DNA topoisomerase II, resulting in an inhibition of the activity of this enzyme. Antibodies to the viral proteins suppressed the inhibitory effects caused by the HIV-1 preparation. Furthermore, the phytohemagglutinin A-caused augmentation of nuclear matrix-associated DNA polymerase alpha and beta activities was found to be abolished by coincubation with the HIV preparation or with the HIV-1 gp120. The phytohemagglutinin A-enhanced matrix association and processivity of DNA polymerase alpha was determined to be reduced if the lymphocytes were in contact with HIV-1 preparation. These results suggest that the reduced proliferative response of lymphocytes to phytohemagglutinin A in the presence of disrupted HIV-1 preparation is due to inhibition of at least two, perhaps separate, pathways, one involving protein kinase C resulting in a reduced phosphorylation of DNA topoisomerase II and the other changing the state of matrix association of DNA polymerase alpha and beta.
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PMID:Effect of nonviable preparations from human immunodeficiency virus type 1 on nuclear matrix-associated DNA polymerase alpha and DNA topoisomerase II activities. 215 2

1. DNA polymerase alpha isolated from Norman murine myxosarcoma exhibited two isozyme forms, one with low specific activity and low DNA binding affinity (A1), and one with high specific activity and high DNA binding affinity (A2). 2. DNA polymerase alpha A1, but not A2, showed a significant increase in specific activity after treatment with phosphatidylinositol, ATP and phosphatidylinositol kinase, or with phosphatidylinositol-4-monophosphate. 3. Treatment of DNA polymerase alpha A1 with the phospholipase C hydrolysis product of phosphatidylinositol-4-monophosphate, inositol-1,4-bisphosphate, was sufficient to effect the transient increase in activity of polymerase A1 to a form not chromatographically distinguishable from isozyme form A2.
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PMID:Interaction of phosphatidylinositol-4-monophosphate with a low activity form of DNA polymerase alpha: a potential mechanism for enzyme activation. 254 77

Since phospholipids have been suggested to play some role in the molecular organisation of the nuclear matrix, the effect of their removal by means of phospholipase C has been investigated in regenerating rat liver nuclear matrix. The matrix-bound DNA polymerase alpha shows an almost complete loss of activity following the digestion with phospholipase C. Since the polymerase activity is restored by adding exogenous DNA, we suggest that the effect is due to the removal of matrix residual DNA, which is in some way linked to the nuclear matrix by means of hydrophobic interactions.
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PMID:Evidence for a reduction of the replicative activity of matrix-bound DNA polymerase alpha following treatment with phospholipase C. 340 34

Investigations of the molecular pharmacology of auranofin (AF) and related gold compounds reveal that these gold complexes interact with proteins primarily via sulfhydryl reactions. Moreover, cell association, distribution and efflux of auranofin and related gold complexes can be explained by sequential sulfhydryl exchanges. The rate of the reactions and potential interactions with sulfhydryl groups in different environments vary according to the ligands associated with the gold. Secondary interactions of AF, such as the formation of triethylphosphine oxide and products of lipid oxidation, may also depend upon characteristics of the ligands. The mechanisms of cytotoxicity by which auranofin and closely related compounds affect cells probably include interactions with key membrane structural proteins, protein crosslinks, and effects on key membrane localized enzymes, e.g., phospholipase C. Other cellular effects may include inhibition of DNA polymerase and other enzymatic processes. Resistance to auranofin is mediated by induction of metallothionein in the cells studied. Gold-loaded metallothionein is less stable to proteolysis than cadmium-bound metallothionein, which probably explains the relatively ephemeral nature of resistance to auranofin.
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PMID:The cellular and molecular pharmacology of auranofin and related gold complexes. 347 75

Human placental extracts contain a specific inhibitor of mammalian retroviral RNA-directed DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) activity. This inhibitor copurifies with retrovirus-like particles in human placental extracts. The inhibitor can be removed from these particles by salt extraction, which leads to the recovery of the polymerase activity. Thus, the inhibitor does not irreversibly inactivate the particle-associated RNA-directed DNA polymerase activity. The inhibitory preparation contained no nuclease, protease, or phosphatase activity. Because its inhibitory action can be eliminated by the addition of more virus to the reaction, nonspecific inactivation of enzyme substrate has been ruled out. A partial characterization of the inhibitor indicates that it is (i) insensitive to ether, trypsin, and phospholipase C; (ii) stable to heat and pH 2-12; and (iii) nondialyzable.
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PMID:Human placentas contain a specific inhibitor of RNA-directed DNA polymerase. 616 15

A polymerase chain reaction (PCR) with thermostable DNA polymerase from Thermus aquaticus is described for the specific amplification of the phospholipase C (alpha-toxin) gene of Clostridium perfringens. A set of primers selected for their high specificity could detect Cl. perfringens in stools with a detection limit of approximately 5 x 10(2) bacteria, after bi-amplification. A modified PCR without thermal steps was performed to rapidly amplify, with a yield of 60%, the DNA template. With this PCR method Cl. perfringens alpha-toxin gene could be detected within 2 h. The PCR method detected alpha-toxin positive Cl. perfringens but did not react with phospholipase C-producing Bacillus cereus, Pseudomonas aeruginosa, Cl. sordellii and Cl. bifermentans. The amplified PCR products were screened through ethidium bromide agarose gel electrophoresis or, in only 1 h, with the PhastSystem (Pharmacia). This PCR satisfies the criteria of specificity, sensitivity and rapidity required for a useful tool in epidemiology and for the diagnosis of the pathogen Cl. perfringens as it may be used directly on stool samples.
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PMID:Detection by in vitro amplification of the alpha-toxin (phospholipase C) gene from Clostridium perfringens. 842 Sep 19

In according with the mechanism for an adaptive response (AR) offered in [Bodnarchuk I.A.//Radiat. biologiya. Radioecologiya. 2002. V. 42. No. 1. P. 36-43], the low-dose irradiation of mammalian cells leads to the activation of such enzymes as Ras, ceramid-activated protein kinase, phospholipase C (PL C) and phosphatidilinostol 3-kinase (PI 3-K). All of them initiate apoptosis and eliminate the most radiosensitive cells form the population before the damaging irradiation. The function of PL C and PI 3-K accompanied by protein kinase C (PK C) activation. PK C activates transcription of the poly(ADP-ribose)polymerase (PARP) gene and DNA polymerase beta gene, and makes posttranslation activation of apurinic/apyrimidinic endonuclease APE, which are participating in the base excision repair (BER). PK C, APE and PARP activate the transcription factor p53, PK C and APE also activate the transcription factor AP-1, AP-1 and p53 take part in the initiation of nucleotide excision reapir (NER). The function of BER, NER and p53 after the damaging irradiation is accompanied by the G1-arrest of cell cycle progression. During G1-arrest there is p53-dependent activation of nonhomologous ends joining (NHEJ) and the inhibition of homologous recombination repair (HRR) of the DNA double-strand breaks takes place. Passing through the NHEJ the cells will outgo from G1-arrest and follow by HRR. AP-1 takes part in outgoing of cells from G1-arrest. So, the preliminary low-dose irradiation causes the decrease of quantity of cells died apoptotically after damaging irradiation as a result of inability to overcome G1-arrest. Thus, AR is the combination of processes: the removal of radiosensitive subpopulation of cells, and/or the activation of DNA repair, and/or the increase of cells ability to overcome the cell cycle delay.
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PMID:[Analysis of the role of DNA repair, regulation of cell cycle and apoptosis in the radiation-induced adaptive response of mammalian cells]. 1267 54

RNA is an important target for drug discovery efforts. Several clinically used aminoglycoside antibiotics bind to bacterial rRNA and inhibit protein synthesis. Aminoglycosides, however, are losing efficacy due to their inherent toxicity and the increase in antibiotic resistance. Targeting of other RNAs is also becoming more attractive thanks to the discovery of new potential RNA drug targets through genome sequencing and biochemical efforts. Identification of new compounds that target RNA is therefore urgent, and we report here on the development of rapid screening methods to probe binding of low molecular weight ligands to proteins and RNAs. A series of aminoglycosides has been immobilized onto glass microscope slides, and binding to proteins and RNAs has been detected by fluorescence. Construction and analysis of the arrays is completed by standard DNA genechip technology. Binding of immobilized aminoglycosides to proteins that are models for study of aminoglycoside toxicity (DNA polymerase and phospholipase C), small RNA oligonucleotide mimics of aminoglycoside binding sites in the ribosome (rRNA A-site mimics), and a large (approximately 400 nucleotide) group I ribozyme RNA is detected. The ability to screen large RNAs alleviates many complications associated with binding experiments that use isolated truncated regions from larger RNAs. These studies lay the foundation for rapid identification of small organic ligands from combinatorial libraries that exhibit strong and selective RNA binding while displaying decreased affinity to toxicity-causing proteins.
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PMID:Aminoglycoside microarrays to explore interactions of antibiotics with RNAs and proteins. 1522 40